38214 Federal Register / Vol. 86, No. 136 / Tuesday, July 20, 2021 / Rules and Regulations 

1This airworthiness directive was eventually 

superseded by AD 2015–21–11, Amendment 39– 

18304 (80 FR 65927, October 28, 2015) (AD 2015– 

21–11). 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0561; Project 

Identifier AD–2021–00623–T; Amendment 

39–21647; AD 2021–14–20] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule; request for 

comments. 

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for all The 

Boeing Company Model 737 airplanes. 

This AD was prompted by reports of 

latent failures of the cabin altitude 

pressure switches. This AD requires 

repetitive functional tests of the 

pressure switches, and on-condition 

actions, including replacement, if 

necessary. The FAA is issuing this AD 

to address the unsafe condition on these 

products. 

DATES: This AD is effective July 20, 

2021. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in this AD 

as of July 20, 2021. 

The FAA must receive comments on 

this AD by September 3, 2021. 

ADDRESSES: You may send comments, 

using the procedures found in 14 CFR 

11.43 and 11.45, by any of the following 

methods: 

• Federal eRulemaking Portal: Go to 

https://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: 202–493–2251. 

• Mail: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue SE, 

Washington, DC 20590. 

• Hand Delivery: Deliver to Mail 

address above between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. 

For service information identified in 

this final rule, contact Boeing 

Commercial Airplanes, Attention: 

Contractual & Data Services (C&DS), 

2600 Westminster Blvd., MC 110–SK57, 

Seal Beach, CA 90740–5600; telephone 

562–797–1717; internet https://

www.myboeingfleet.com. You may view 

this service information at the FAA, 

Airworthiness Products Section, 

Operational Safety Branch, 2200 South 

216th St., Des Moines, WA. For 

information on the availability of this 

material at the FAA, call 206–231–3195. 

It is also available at https://

www.regulations.gov by searching for 

and locating Docket No. FAA–2021– 

0561. 

Examining the AD Docket 

You may examine the AD docket at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA–2021–0561; or in person at Docket 

Operations between 9 a.m. and 5 p.m., 

Monday through Friday, except Federal 

holidays. The AD docket contains this 

final rule, any comments received, and 

other information. The street address for 

Docket Operations is listed above. 

FOR FURTHER INFORMATION CONTACT: 

Nicole Tsang, Aerospace Engineer, 

Cabin Safety and Environmental 

Systems Section, FAA, Seattle ACO 

Branch, 2200 South 216th St., Des 

Moines, WA 98198; phone and fax: 206– 

231–3959; email: Nicole.S.Tsang@

faa.gov. 

SUPPLEMENTARY INFORMATION: 

Background 

The FAA requires every proposed 

transport category airplane design with 

a pressurized cabin to include a system 

that warns the flightcrew of cabin 

depressurization. 14 CFR 25.841(b). On 

Boeing Model 737 airplanes, such 

warning systems include a cabin 

altitude pressure switch. The functions 

of this pressure switch are twofold: To 

detect if a certain cabin pressure 

altitude has been exceeded; and if so, to 

send a signal to the parts of the system 

that provide aural and visual warnings 

to the flightcrew. When this switch fails, 

it fails latently; that is, without making 

the failure known to the flightcrew or 

maintenance personnel. Due to the 

importance of the functions provided by 

this switch, in 2012 the FAA mandated 

that all Boeing Model 737 airplanes 

utilize two switches, to provide 

redundancy in case of one switch’s 

failure. AD 2012–19–11, Amendment 

39–17206 (77 FR 60296, October 3, 

2012).1

The FAA has received reports of 

latent failures of these cabin altitude 

pressure switches. In September 2020, 

an operator reported that on three of its 

airplanes, both pressure switches failed 

the on-wing functional test. The affected 

switches were on three different models 

of the Boeing 737. 

The airplane manufacturer 

investigated, and initially found, for 

reasons that included the expected 

failure rate of the switches, that it did 

not pose a safety issue. Boeing decided 

in November 2020 that the failures were 

not a safety issue. Subsequent 

investigation and analysis led the FAA 

and the airplane manufacturer to 

determine, in May of 2021, that the 

failure rate of both switches is much 

higher than initially estimated, and 

therefore does pose a safety issue. 

The FAA does not yet have sufficient 

information to determine what has 

caused this unexpectedly high failure 

rate, so a terminating corrective action 

cannot yet be developed. However, a 

latent failure of both pressure switches 

could result in the loss of cabin altitude 

warning, which could delay flightcrew 

recognition of a lack of cabin 

pressurization, and result in 

incapacitation of the flightcrew due to 

hypoxia (a lack of oxygen in the body), 

and consequent loss of control of the 

airplane. Therefore addressing these 

failures requires immediate action. The 

FAA is issuing this AD to address the 

unsafe condition on these products. 

FAA’s Determination 

The FAA is issuing this AD because 

the agency has determined the unsafe 

condition described previously is likely 

to exist or develop in other products of 

the same type design. 

Related Service Information Under 1 

CFR Part 51 

The FAA reviewed Boeing Multi 

Operator Message MOM–MOM–21– 

0292–01B, dated June 23, 2021. This 

service information specifies procedures 

for repetitive functional tests of the 

cabin altitude pressure switches, oncondition actions including follow-on 

functional testing and replacement of 

failed switches, sending a report to 

Boeing about any pressure switches that 

fail the initial functional test, and 

reporting to Boeing the airplanes in the 

operator’s fleet that have been tested. 

This service information is reasonably 

available because the interested parties 

have access to it through their normal 

course of business or by the means 

identified in the ADDRESSES section. 

AD Requirements 

This AD requires accomplishing the 

actions specified in the service 

information already described, except as 

discussed under ‘‘Differences Between 

this AD and the Service Information.’’ 

This AD also requires reporting to 

Boeing the results of the first functional 

test if any pressure switch failed, and 

sending reports to Boeing of the 

airplanes in the operator’s fleet that 

have been tested. 


khammond on DSKJM1Z7X2PROD with RULES
Federal Register / Vol. 86, No. 136 / Tuesday, July 20, 2021 / Rules and Regulations 38215 

Effect of Certain Installation Procedures 

on Accomplishment of AD 

Requirements 

As previously noted, the FAA issued 

AD 2015–21–11, applicable to certain 

Model 737–100, –200, –200C, –300, 

–400, –500, –600, –700, –700C, –800,

–900, and –900ER series airplanes. AD

2015–21–11 requires, among other

actions, the installation of a redundant

cabin altitude pressure switch in

accordance with specified Boeing

service information. The FAA has since

approved numerous supplemental type

certificates (STCs) and other means for

installing the redundant pressure

switch. As a result of its oversight of

these newly-installed switches, the FAA

has determined that use of approved

maintenance procedures for the cabin

altitude pressure switch functional test

other than those specified in the task

cards identified in Boeing Multi

Operator Message MOM–MOM–21–

0292–01B, dated June 23, 2021, is

acceptable for the functional test;

therefore, those other procedures do not

require approval of an alternative

method of compliance (AMOC).

Differences Between This AD and the 

Service Information 

Although Boeing Multi Operator 

Message MOM–MOM–21–0292–01B, 

dated June 23, 2021, affects ‘‘all 737CL’’ 

airplanes (the 737 Classics include 

Model 737–100, –200, –200C, –300, 

–400, and –500), Boeing did not send

the MOM to Model 737–100, –200 and

–200C operators. Additionally, Boeing

did not reference procedures for

performing the cabin altitude pressure

switch functional test for Model 737–

100, –200, and –200C series airplanes.

There are no Model 737–100 series

airplanes operating worldwide;

however, the applicability of this AD

includes those airplanes in the event

any of those airplanes are returned to

service in the U.S. The FAA has also

included Model 737–200 and –200C

series airplanes in the applicability of

this AD. Furthermore, the FAA

requested that Boeing make the service

information available to Model 737–200

and –200C operators. Boeing Model

737–200 and –200C operators may

reference 737–200 Airplane

Maintenance Manual (AMM) 21–33–11/

501 for additional guidance on

performing the cabin altitude pressure

switch functional test.

Boeing Multi Operator Message 

MOM–MOM–21–0292–01B, dated June 

23, 2021, uses permissive language, 

such as ‘‘recommends’’ and 

‘‘requesting,’’ in its ‘‘Functional Test 

Requirements’’ and ‘‘Reporting 

Requirements’’ sections. However, the 

regulatory text in paragraphs (g) and (h) 

of this AD makes the language in those 

sections mandatory unless an exception 

in paragraph (j) of this AD applies. 

Boeing Multi Operator Message 

MOM–MOM–21–0292–01B, dated June 

23, 2021, recommends returning failed 

pressure switches to the switch 

manufacturer. Although the FAA also 

recommends that operators return failed 

pressure switches in order to provide 

the switch manufacturer with additional 

data related to the unsafe condition, this 

AD does not require that action. 

Although Boeing Multi Operator 

Message MOM–MOM–21–0292–01B, 

dated June 23, 2021, identifies specific 

AMM task cards for use in 

accomplishing the functional test, 

paragraph (j)(1) of this AD clarifies that 

any approved maintenance procedures 

may be used for the functional test. This 

provides the operator an option to use 

the AMM task card or any approved 

maintenance procedure for the 

functional test without needing to 

request an AMOC. 

Boeing Multi Operator Message 

MOM–MOM–21–0292–01B, dated June 

23, 2021, specifies certain on-condition 

actions, including an additional step 

while performing the functional test on 

the switch by increasing the altitude 

setting on the switch to an altitude of up 

to 20,000 feet if the cabin altitude 

warning does not activate by 11,000 feet 

during the initial functional test. The 

service information specifies repeating 

the functional test at intervals, but does 

not explicitly state that the on-condition 

additional functional testing is limited 

to the initial functional test only. 

Paragraph (j)(3) of this AD requires the 

on-condition additional functional test 

step of increasing the altitude setting to 

20,000 feet only during the initial 

functional test (if applicable). 

Although Boeing Multi Operator 

Message MOM–MOM–21–0292–01B, 

dated June 23, 2021, specifies that failed 

switches be replaced with ‘‘new or 

serviceable’’ switches, this AD requires 

replacement with ‘‘serviceable’’ 

switches, which include any switches 

that are eligible for installation. This is 

to ensure that any installed switch is 

serviceable. 

Interim Action 

The FAA considers this AD to be an 

interim action. The reporting that is 

required by this AD will enable the 

airplane manufacturer to obtain better 

insight into the nature, cause, and 

extent of the switch failures, and 

eventually to develop final action to 

address the unsafe condition. Once final 

action has been identified, the FAA 

might consider further rulemaking. 

Justification for Immediate Adoption 

and Determination of the Effective Date 

Section 553(b)(3)(B) of the 

Administrative Procedure Act (APA) (5 

U.S.C. 551 et seq.) authorizes agencies 

to dispense with notice and comment 

procedures for rules when the agency, 

for ‘‘good cause,’’ finds that those 

procedures are ‘‘impracticable, 

unnecessary, or contrary to the public 

interest.’’ Under this section, an agency, 

upon finding good cause, may issue a 

final rule without providing notice and 

seeking comment prior to issuance. 

Further, section 553(d) of the APA 

authorizes agencies to make rules 

effective in less than thirty days, upon 

a finding of good cause. 

An unsafe condition exists that 

requires the immediate adoption of this 

AD without providing an opportunity 

for public comments prior to adoption. 

The FAA has found that the risk to the 

flying public justifies forgoing notice 

and comment prior to adoption of this 

rule because, as previously noted, the 

unexpectedly high rate of latent failure, 

of both pressure switches on the same 

airplane, could result in the cabin 

altitude warning system not activating if 

the cabin altitude exceeds 10,000 feet, 

resulting in hypoxia of the flightcrew, 

and loss of control of the airplane. 

Accordingly, notice and opportunity for 

prior public comment are impracticable 

and contrary to the public interest 

pursuant to 5 U.S.C. 553(b)(3)(B). 

In addition, the FAA finds that good 

cause exists pursuant to 5 U.S.C. 553(d) 

for making this amendment effective in 

less than 30 days, for the same reasons 

the FAA found good cause to forgo 

notice and comment. 

Comments Invited 

The FAA invites you to send any 

written data, views, or arguments about 

this final rule. Send your comments to 

an address listed under ADDRESSES. 

Include Docket No. FAA–2021–0561 

and Project Identifier AD–2021–00623– 

T at the beginning of your comments. 

The most helpful comments reference a 

specific portion of the final rule, explain 

the reason for any recommended 

change, and include supporting data. 

The FAA will consider all comments 

received by the closing date and may 

amend this final rule because of those 

comments. 

Except for Confidential Business 

Information (CBI) as described in the 

following paragraph, and other 

information as described in 14 CFR 

11.35, the FAA will post all comments 

received, without change, to https:// 


khammond on DSKJM1Z7X2PROD with RULES
38216 Federal Register / Vol. 86, No. 136 / Tuesday, July 20, 2021 / Rules and Regulations 

www.regulations.gov, including any 

personal information you provide. The 

agency will also post a report 

summarizing each substantive verbal 

contact received about this final rule. 

Confidential Business Information 

CBI is commercial or financial 

information that is both customarily and 

actually treated as private by its owner. 

Under the Freedom of Information Act 

(FOIA) (5 U.S.C. 552), CBI is exempt 

from public disclosure. If your 

comments responsive to this AD contain 

commercial or financial information 

that is customarily treated as private, 

that you actually treat as private, and 

that is relevant or responsive to this AD, 

it is important that you clearly designate 

the submitted comments as CBI. Please 

mark each page of your submission 

containing CBI as ‘‘PROPIN.’’ The FAA 

will treat such marked submissions as 

confidential under the FOIA, and they 

will not be placed in the public docket 

of this AD. Submissions containing CBI 

should be sent to Nicole Tsang, 

Aerospace Engineer, Cabin Safety and 

Environmental Systems Section, FAA, 

Seattle ACO Branch, 2200 South 216th 

St., Des Moines, WA 98198; phone and 

fax: 206–231–3959; email: 

Nicole.S.Tsang@faa.gov. Any 

commentary that the FAA receives that 

is not specifically designated as CBI will 

be placed in the public docket for this 

rulemaking. 

Regulatory Flexibility Act 

The requirements of the Regulatory 

Flexibility Act (RFA) do not apply when 

an agency finds good cause pursuant to 

5 U.S.C. 553 to adopt a rule without 

prior notice and comment. Because the 

FAA has determined that it has good 

cause to adopt this rule without notice 

and comment, RFA analysis is not 

required. 

Costs of Compliance 

The FAA estimates that this AD 

affects 2,502 airplanes of U.S. registry. 

The FAA estimates the following costs 

to comply with this AD: 

ESTIMATED COSTS

Action Labor cost Parts cost Cost per 

product 

Cost on U.S. 

operators 

Functional test ........ 1 work-hour × $85 per hour = $85 per test ................................... $0 $85 per test ... $212,670 per test. 

In addition, the FAA has determined 

that preparing and sending a monthly 

report of tested airplanes takes about 1 

work-hour per operator. Since operators 

are required to submit this report for 

their affected fleet(s), the FAA has 

determined that a per-operator estimate 

is more appropriate than a per-airplane 

estimate. Therefore, the FAA estimates 

the average total cost of the monthly 

report to be $85 (1 work-hour × $85) per 

report, per operator. 

The FAA estimates the following 

costs to do any necessary on-condition 

actions that would be required based on 

the results of the functional test. The 

FAA has no way of determining the 

number of aircraft that might need these 

actions: 

ON-CONDITION COSTS

Action Labor cost Parts cost Cost per 

product 

On-condition functional test and switch replacement .. 1 work-hour × $85 per hour = $85 ............................... $1,278 $1,363 

Reporting ...................................................................... 1 work-hour × $85 per hour = $85 ............................... 0 85 

Paperwork Reduction Act 

A federal agency may not conduct or 

sponsor, and a person is not required to 

respond to, nor shall a person be subject 

to a penalty for failure to comply with 

a collection of information subject to the 

requirements of the Paperwork 

Reduction Act unless that collection of 

information displays a currently valid 

OMB Control Number. The OMB 

Control Number for this information 

collection is 2120–0056. Public 

reporting for this collection of 

information is estimated to be 

approximately 1 hour per response, 

including the time for reviewing 

instructions, searching existing data 

sources, gathering and maintaining the 

data needed, completing and reviewing 

the collection of information. All 

responses to this collection of 

information are mandatory. Send 

comments regarding this burden 

estimate or any other aspect of this 

collection of information, including 

suggestions for reducing this burden to: 

Information Collection Clearance 

Officer, Federal Aviation 

Administration, 10101 Hillwood 

Parkway, Fort Worth, TX 76177–1524. 

Authority for This Rulemaking 

Title 49 of the United States Code 

specifies the FAA’s authority to issue 

rules on aviation safety. Subtitle I, 

section 106, describes the authority of 

the FAA Administrator. Subtitle VII: 

Aviation Programs describes in more 

detail the scope of the Agency’s 

authority. 

The FAA is issuing this rulemaking 

under the authority described in 

Subtitle VII, Part A, Subpart III, Section 

44701: General requirements. Under 

that section, Congress charges the FAA 

with promoting safe flight of civil 

aircraft in air commerce by prescribing 

regulations for practices, methods, and 

procedures the Administrator finds 

necessary for safety in air commerce. 

This regulation is within the scope of 

that authority because it addresses an 

unsafe condition that is likely to exist or 

develop on products identified in this 

rulemaking action. 

Regulatory Findings 

This AD will not have federalism 

implications under Executive Order 

13132. This AD will not have a 

substantial direct effect on the States, on 

the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government. 

For the reasons discussed above, I 

certify that this AD: 

(1) Is not a ‘‘significant regulatory

action’’ under Executive Order 12866, 

and 

(2) Will not affect intrastate aviation

in Alaska. 


khammond on DSKJM1Z7X2PROD with RULES
Federal Register / Vol. 86, No. 136 / Tuesday, July 20, 2021 / Rules and Regulations 38217 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

Safety. 

Adoption of the Amendment 

Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA amends 14 CFR part 39 as 

follows: 

PART 39—AIRWORTHINESS 

DIRECTIVES 

■ 1. The authority citation for part 39 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive: 

2021–14–20 The Boeing Company: 

Amendment 39–21647; Docket No. 

FAA–2021–0561; Project Identifier AD– 

2021–00623–T. 

(a) Effective Date 

This airworthiness directive (AD) is 

effective July 20, 2021. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to all The Boeing 

Company Model 737 airplanes, certificated in 

any category. 

(d) Subject 

Air Transport Association (ATA) of 

America Code 21, Air conditioning. 

(e) Unsafe Condition 

This AD was prompted by reports of latent 

failures of the cabin altitude pressure 

switches. The FAA is issuing this AD to 

address the unexpectedly high rate of latent 

failure of both pressure switches on the same 

airplane which could result in the cabin 

altitude warning system not activating if the 

cabin altitude exceeds 10,000 feet, resulting 

in hypoxia of the flightcrew, and loss of 

control of the airplane. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Repetitive Functional Tests 

Except as specified in paragraph (j) of this 

AD: At the latest of the times specified in 

paragraphs (g)(1) through (3) of this AD, 

perform the initial functional test of the cabin 

altitude pressure switches, and before further 

flight, do all applicable on-condition actions, 

in accordance with the ‘‘Functional Test 

Requirements’’ section of Boeing Multi 

Operator Message MOM–MOM–21–0292– 

01B, dated June 23, 2021. Repeat the 

functional test thereafter at intervals not to 

exceed 2,000 flight hours and do all 

applicable on condition actions before 

further flight. 

(1) Within 2,000 flight hours since the last 

functional test of the cabin altitude pressure 

switches. 

(2) Prior to the accumulation of 2,000 total 

flight hours on the airplane. 

(3) Within 90 days after the effective date 

of this AD. 

Note 1 to paragraph (g): Additional 

guidance for performing the functional test 

required by paragraph (g) of this AD can be 

found in 737–200 Airplane Maintenance 

Manual (AMM) 21–33–11/501, 737CL AMM 

TASK CARD 31–026–01–01, 737CL AMM 

TASK CARD 31–010–01–01, 737NG AMM 

TASK CARD 31–020–00–01, and 737MAX 

AMM TASK CARD 31–020–00–01, and other 

approved maintenance procedures. 

(h) Reporting for Switch Failure 

If any switch fails the initial functional test 

required by paragraph (g) of this AD: At the 

applicable time specified in paragraph (h)(1) 

or (2) of this AD, report the results of that 

functional test, in accordance with Boeing 

Multi Operator Message MOM–MOM–21– 

0292–01B, dated June 23, 2021. 

(1) If the functional test was done on or 

after the effective date of this AD: Submit the 

report within 10 days after the functional 

test. 

(2) If the functional test was done before 

the effective date of this AD: Submit the 

report within 10 days after the effective date 

of this AD. 

(i) Repetitive Reporting of Tested Fleet 

Within 40 days, but no earlier than 30 

days, after the effective date of this AD: Send 

a report to Boeing listing the total number of 

airplanes, including tail numbers, in the 

operator’s fleet that have been tested since 

the effective date of this AD, in accordance 

with Boeing Multi Operator Message MOM– 

MOM–21–0292–01B, dated June 23, 2021. 

Thereafter, send a report for the number of 

airplanes tested, at intervals of 30 days for a 

total period of 12 months. A report is not 

required for any 30-day interval in which no 

airplanes were tested. 

(j) Exceptions to Service Information 

Specifications 

(1) Where Boeing Multi Operator Message 

MOM–MOM–21–0292–01B, dated June 23, 

2021, refers to certain task cards for the 

functional test, that service information is not 

required by this AD, and any approved 

maintenance procedures are acceptable for 

the functional test. 

(2) Where Boeing Multi Operator Message 

MOM–MOM–21–0292–01B, dated June 23, 

2021, specifies replacing failed switches with 

‘‘new or serviceable’’ switches, this AD 

requires replacement with ‘‘serviceable’’ 

switches, which include any switches that 

are eligible for installation. 

(3) Where Boeing Multi Operator Message 

MOM–MOM–21–0292–01B, dated June 23, 

2021, specifies the on-condition additional 

step of increasing the altitude to 20,000 feet 

if the cabin altitude warning does not 

activate by 11,000 feet, this AD requires that 

additional step only during the initial 

functional test. 

(k) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Seattle ACO Branch, 

FAA, has the authority to approve AMOCs 

for this AD, if requested using the procedures 

found in 14 CFR 39.19. In accordance with 

14 CFR 39.19, send your request to your 

principal inspector or responsible Flight 

Standards Office, as appropriate. If sending 

information directly to the manager of the 

certification office, send it to the attention of 

the person identified in Related Information. 

Information may be emailed to 9-ANMSeattle-ACO-AMOC-Requests@faa.gov. 

(2) Before using any approved AMOC, 

notify your appropriate principal inspector, 

or lacking a principal inspector, the manager 

of the responsible Flight Standards Office. 

(3) An AMOC that provides an acceptable 

level of safety may be used for any repair, 

modification, or alteration required by this 

AD if it is approved by The Boeing Company 

Organization Designation Authorization 

(ODA) that has been authorized by the 

Manager, Seattle ACO Branch, FAA, to make 

those findings. To be approved, the repair 

method, modification deviation, or alteration 

deviation must meet the certification basis of 

the airplane, and the approval must 

specifically refer to this AD. 

(l) Related Information 

For more information about this AD, 

contact Nicole Tsang, Aerospace Engineer, 

Cabin Safety and Environmental Systems 

Section, FAA, Seattle ACO Branch, 2200 

South 216th St., Des Moines, WA 98198; 

phone and fax: 206–231–3959; email: 

Nicole.S.Tsang@faa.gov. 

(m) Material Incorporated by Reference 

(1) The Director of the Federal Register 

approved the incorporation by reference 

(IBR) of the service information listed in this 

paragraph under 5 U.S.C. 552(a) and 1 CFR 

part 51. 

(2) You must use this service information 

as applicable to do the actions required by 

this AD, unless the AD specifies otherwise. 

(i) Boeing Multi Operator Message MOM– 

MOM–21–0292–01B, dated June 23, 2021. 

(ii) [Reserved] 

(3) For service information identified in 

this AD, contact Boeing Commercial 

Airplanes, Attention: Contractual & Data 

Services (C&DS), 2600 Westminster Blvd., 

MC 110–SK57, Seal Beach, CA 90740–5600; 

telephone 562–797–1717; internet https://

www.myboeingfleet.com. 

(4) You may view this service information 

at the FAA, Airworthiness Products Section, 

Operational Safety Branch, 2200 South 216th 

St., Des Moines, WA. For information on the 

availability of this material at the FAA, call 

206–231–3195. 

(5) You may view this service information 

that is incorporated by reference at the 

National Archives and Records 

Administration (NARA). For information on 

the availability of this material at NARA, 

email fedreg.legal@nara.gov, or go to: https:// 

www.archives.gov/federal-register/cfr/ibrlocations.html. 


khammond on DSKJM1Z7X2PROD with RULES
38218 Federal Register / Vol. 86, No. 136 / Tuesday, July 20, 2021 / Rules and Regulations 

Issued on July 2, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–15391 Filed 7–15–21; 4:15 pm] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0348; Project 

Identifier 2018–SW–076–AD; Amendment 

39–21645; AD 2021–14–18] 

RIN 2120–AA64 

Airworthiness Directives; Leonardo 

S.p.a. (Type Certificate Previously Held 

by Agusta S.p.A.) Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: The FAA is superseding 

Airworthiness Directive (AD) 2011–18– 

52 for certain Agusta S.p.A. (now 

Leonardo S.p.a.) Model AB139 and 

AW139 helicopters. AD 2011–18–52 

required revising the life limit for 

certain part-numbered tail rotor (T/R) 

blades, updating the helicopter’s 

historical records, repetitively 

inspecting each T/R blade for a crack or 

damage, and depending on the results, 

replacing the T/R blade. This AD was 

prompted by the manufacturer 

developing improved T/R blades using 

different materials and establishing life 

limits for each improved blade. This AD 

retains certain requirements from AD 

2011–18–52, revises certain 

requirements from AD 2011–18–52, and 

expands the applicability to include the 

newly-designed T/R blades. The FAA is 

issuing this AD to address the unsafe 

condition on these products. 

DATES: This AD is effective August 24, 

2021. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in this AD 

as of August 24, 2021. 

ADDRESSES: For service information 

identified in this final rule, contact 

Leonardo S.p.A. Helicopters, Emanuele 

Bufano, Head of Airworthiness, Viale 

G.Agusta 520, 21017 C. Costa di 

Samarate (Va) Italy; telephone +39– 

0331–225074; fax +39–0331–229046; or 

at https://www.leonardocompany.com/ 

en/home. You may view this service 

information at the FAA, Office of the 

Regional Counsel, Southwest Region, 

10101 Hillwood Pkwy., Room 6N–321, 

Fort Worth, TX 76177. For information 

on the availability of this material at the 

FAA, call (817) 222–5110. It is also 

available at https://www.regulations.gov 

by searching for and locating Docket No. 

FAA–2021–0348. 

Examining the AD Docket 

You may examine the AD docket at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA–2021–0348; or in person at Docket 

Operations between 9 a.m. and 5 p.m., 

Monday through Friday, except Federal 

holidays. The AD docket contains this 

final rule, the European Aviation Safety 

Agency (now European Union Aviation 

Safety Agency) (EASA) AD, any 

comments received, and other 

information. The address for Docket 

Operations is U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue SE, 

Washington, DC 20590. 

FOR FURTHER INFORMATION CONTACT: Matt 

Fuller, AD Program Manager, General 

Aviation & Rotorcraft Unit, 

Airworthiness Products Section, 

Operational Safety Branch, FAA, 10101 

Hillwood Pkwy., Fort Worth, TX 76177; 

telephone (817) 222–5110; email 

matthew.fuller@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Background 

The FAA issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 to supersede AD 2011–18–52, 

Amendment 39–17020 (77 FR 23109, 

April 18, 2012) (AD 2011–18–52). AD 

2011–18–52 applied to Agusta S.p.A. 

(now Leonardo S.p.a.) Model AB139 

and AW139 helicopters with a T/R 

blade part number (P/N) 3G6410A00131 

or P/N 4G6410A00131 installed. The 

NPRM published in the Federal 

Register on May 10, 2021 (86 FR 24780). 

AD 2011–18–52 required, within 5 

hours time-in-service (TIS), establishing 

a life limit of 600 hours TIS or 1,500 

takeoff and landing cycles (cycles), 

whichever occurs first, on the affected 

T/R blades and updating the 

helicopter’s historical records. If a T/R 

blade’s total number of cycles was 

unknown, determining the T/R blade 

cycles by multiplying the T/R blade’s 

hours TIS by 4 was required. For a T/ 

R blade that, on the effective date of AD 

2011–18–52, had already exceeded 600 

hours TIS or 1,500 cycles, the AD 

required replacing the T/R blade with 

an airworthy T/R blade within 5 hours 

TIS. 

AD 2011–18–52 also required, within 

25 hours TIS, and thereafter at intervals 

not to exceed 25 hours TIS, inspecting 

the T/R blade for a crack or damage that 

exceeds the limits of the applicable 

maintenance manual. The inspection 

was required to be accomplished using 

a mirror, magnifying glass (5X or 

greater), and light source; or borescope. 

If there was a crack, or if there was 

damage that exceeded the limits of the 

applicable maintenance manual, AD 

2011–18–52 required, before further 

flight, replacing the T/R blade with an 

airworthy T/R blade. 

AD 2011–18–52 was prompted by a 

fatal accident involving an Agusta 

Model AW139 helicopter, which may 

have been caused by cracks in a T/R 

blade. EASA, which is the Technical 

Agent for the Member States of the 

European Union, issued EASA 

Emergency AD 2011–0156–E, dated 

August 25, 2011 (EASA AD 2011–0156– 

E) to require repetitive inspections and 

reducing the life limit of the T/R blades. 

According to EASA, this condition, if 

not detected and corrected, could result 

in failure of a T/R blade and subsequent 

loss of control of the helicopter. 

After the FAA issued AD 2011–18–52, 

EASA issued a series of ADs as follows: 

• EASA AD 2012–0030, dated 

February 17, 2012 (EASA AD 2012– 

0030), which superseded Emergency AD 

2011–0156–E, advised that the 

manufacturer developed improved, 

newly-designed T/R blades P/N 

3G6410A00132 and P/N 

4G6410A00132, established life limits 

for each improved T/R blade, added 

repetitive inspections for the improved 

T/R blades, and advised that each T/R 

blade P/N had its own individual life 

limit. 

• EASA AD 2012–0076, dated May 2, 

2012 (EASA AD 2012–0076), which 

superseded EASA AD 2012–0030 and 

was issued after the manufacturer 

developed another version of improved 

T/R blades P/N 3G6410A00133 and P/ 

N 4G6410A00133 with different 

materials. AD 2012–0076 required 

interim life limits for the new improved 

version of the T/R blades while also 

retaining the inspection requirements of 

EASA AD 2012–0030. 

• EASA AD 2012–0076R1, dated July 

13, 2012 (EASA AD 2012–0076R1), 

which revised EASA AD 2012–0076 

after a modification was developed to 

allow installation of certain partnumbered 

T/R blades under certain conditions. 

• EASA AD 2012–0076R2, dated 

February 20, 2014 (EASA AD 2012– 

0076R2), which revised EASA AD 

2012–0076R1, was issued after another 

modification was developed. EASA AD 

2012–0076R2 requires removing the 25 

hours TIS inspection of certain partnumbered T/R blades, extending the life 


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